In the alkaline pulping process, wood chips are digested in an aqueous pulping liquor containing sodium hydroxide. If the liquor also contains sodium sulfide, the process is kraft. After digestion is complete, the spent liquor (called black liquor) is concentrated by evaporation. The organic matter in the concentrated black liquor is then burned and the resulting smelt is dissolved in water to produce green liquor, which contains sodium carbonate. After being clarified, the green liquor is causticized by combining it with lime (calcium oxide) to convert the sodium carbonate to sodium hydroxide. The causticized liquor (called white liquor) is then used to digest more wood. This invention provides a more direct process for removing the organic matter in spent pulping liquor and regenerating the inorganic chemical values in the liquor.